Earlier this month the Unite union passed a resolution denouncing Israel as an apartheid regime, supporting boycotts against it and accusing it of "feeling able to commit war crimes with complete impunity". When Israel launched its latest operation in Gaza, the union issued a statement to "unreservedly condemn the continuing Israeli aggression against the Palestinian people".

This savaging of Israel by Britain's largest trade union is deeply disturbing. It follows days of distressing images of the awful civilian casualties in the Gaza strip screened around the clock in the British media.

Israelis too are exposed to many of these images. Here too they cause great anguish and soul searching. At the heart of Jewish belief lies the idea that every human being is created in the divine image, every person is of infinite value and no innocent human being should suffer. The shofar blown on Rosh Hashanah echoes the sound of the weeping of a mother for her son Sisera, the mortal enemy of the Jewish people who was killed as he fled the battlefield.

But for most of us now, the focus is different. As missiles are fired daily at Israel's major cities, our priority is protecting our children and elderly relatives who struggle to reach the safety of an air-raid shelter in the few seconds between the wail of the siren and the potentially lethal attack.

Meanwhile, our children are sent to the front. In Jewish tradition, a war fought to protect Israel from an enemy attacks is just. Jewish soldiers serving in a just war must battle and kill according to the normal rules of combat. Were the same soldiers to fight an unjust war, they would not only miss out on the heroic acclaim, they would actually be murderers.

This fear that participation in war might sully one's humanity and spirituality is, according to our biblical commentators, a theme in the lives of our ancestors. Jacob, for example, while awaiting a showdown with his belligerent brother Esau, spent the night in fear and terror - fear, say the rabbis, that he would be killed and terror that he would be forced to take the life of his own brother.

Jacob made peace with his brother and seems to have got away unblemished from the experience. King David was not so lucky. While lauded as our greatest king, he still paid the price for his military prowess when he was barred from building the Temple because he had shed too much blood.

Others took a more cautious approach. Moses, our greatest leader and prophet, was so gentle that when he received the divine command to attack Sihon, one of Israel's most detested enemies, he took it on himself to override God's instructions and pre-empt the attack with an offer of peace. According to the Midrash, God was so touched by this humanitarian act, that he enshrined the principle within halachah; a Jewish army may never go out to war without first suing for peace (Bemidbar Rabbah 19: 33).

This caution is not just a matter of super-piety, but a sensible act of pragmatism. Commenting on the many precautions the Torah demands to protect innocent civilians and ensure the purity of a military camp, the Ramban warns that the chaos of war creates the potential for any soldier to lose control: "The fairest of men by nature comes to be possessed of cruelty and fury when the army advances against the enemy" . These laws, he suggests, not only to help save lives, but also to teach Jewish soldiers the importance of compassion, even for our enemies.

While Jewish soldiers have moral duties to our enemies, a Jewish government also has responsibilities to its home front. This rests on a fundamental biblical principle of self-defence: "If someone is approaching to kill you, then get up and kill them first" (Exodus 22:1). If this seems harsh, the rabbis reasoned that failure to deal with a lethal attacker would only result in future casualties - "One who is merciful to the cruel will end up being cruel to the merciful".

With a daily barrage of ever more advanced missiles flying in from Gaza, most Israelis feel that failure to knock out these rockets will lead to further fatalities.

Israel was established on the basis of equality and freedom for all its citizens; we must ensure our government unceasingly pursues those goals and the search for peace. That is difficult when our citizens face an enemy fuelled by religious fervour which has no willingness to compromise. But our tradition assures us that eventually peace will come.

Israel's conflict with the Palestinians is complex and needs to be peacefully resolved as soon as possible, giving security, justice and freedom to all. That cause is not served by vicious attacks on Israel and unfair presentations of the conflict by misinformed trade unionists or journalists hungry for their next scoop.